In modern motor vehicles, the windshields are fixedly joined to a perimeter body flange by a bead of adhesive made of a polyurethane adhesive or some other suitable adhesive. The bead of adhesive consists of such a strong adhesive that, in combination with the windshield, even the mechanical stability of the vehicle is augmented. It is self-evident, therefore, that severing the adhesive is relatively complicated due to its high strength and toughness.
Since windshields must frequently be replaced because of stone chipping or other types of damage, it is necessary to provide a suitable device and/or a suitable method for removing the glass pane of the windshield.
In many cases, a cutting knife of U-shaped cross-section, by means of which the bead of adhesive is successively severed, has been used for this purpose (see U.S. Pat. No. 4,980,976).
Although such a device and such a method have enabled the bead of adhesive of a windshield to be severed in a satisfactory manner, the gap between the windshield and the body flange has become increasingly narrow in recent years. In many cases, it is no longer possible to use such cutting knives, which are used in combination with an oscillatory drive, in order to sever the bead of adhesive.
Numerous other methods and devices are known for severing the bead of adhesive with the aid of a cutting wire.
The bead of adhesive can be severed, for example, with the aid of a cutting wire fitted with two handles (see U.S. Pat. Nos. 4,995,153 and 2003/0217471 A1).
The specific disadvantage of such a method is that two persons are always needed to sever the bead of adhesive. One person must operate a handle inside the vehicle and one person a handle outside the vehicle. It is also obvious that such a manner of working requires a considerable amount of time and is very tiring on account of the effort involved.
A device and method for severing the bead of adhesive with the aid of a cutting wire, with only one person being needed to sever the bead, is known from U.S. Pat. No. 6,591,502 B1. A suction cup to which a cutting wire is elastically fixed with the aid of a spring is placed onto the windshield. The cutting wire is pulled to the outside using a handle in order to sever the bead bit by bit. The force applied is reduced released after each pull, with the result that the cutting wire is retracted under the force of the compressed spring.
This has the advantage that the severing process can be carried out by only one person. However, a considerable amount of time and energy is still required. A similar assessment can be made of the windshield removal system known from U.S. Pat. No. 5,622,093. Here, too, a suction cup assembly is placed onto the windshield, a cutting wire being fixed to the suction cup via a spring that has a handle at its outer end. The spring is attached to a swivel head that is bidirectionally rotatable about 360° in approximately the same plane as the windshield. In this case also, the cutting wire is pulled with the aid of the handle and alternately retracted under the effect of the spring and the swivel head. This method is likewise relatively time-consuming and tiring for the worker.
From DE 32 15 892 A1 a device for severing a bead of adhesive using a winding device placed inside the vehicle into which the cutting wire is reeled in is known.
However, still considerable skill of the worker is needed to effect severing of the bead when using such a device.